The multilayered photon detector structure of the present invention is fully described in U.S. Pat. No. 4,268,750, issued to Ronald Cowart on May 19, 1981. U.S. Pat. No. 4,268,750 describes an X-ray film replacement comprising a sandwich detector structure; a method of converting the latent radiographic image stored by such a detector to an electric video signal; an apparatus capable of practicing the method; and a diagnostic X-ray system using the apparatus. The detector sandwich comprises a conductive backplate overlaid by a photoconductive layer; for example, a layer of amorphous selenium having high effective dark resistivity. This high effective dark resistivity is accomplished by forming a blocking layer between the photoconductor and the conductive backplate. The photoconductor is overlaid by an insulator which is covered by a transparent conductive film. A further and more complete explanation of the operation and arrangement of the multilayered detector structure and accompanying optics is contained within this patent.
The method of reading out the multilayered detector structure of U.S. Pat. No. 4,268,750 utilizes a rotating multi-sided mirror. The mirror is mounted on an axis operably attached to a scanning motor which rotates the multi-sided mirror on its axis so as to cause a laser/light source to scan horizontally across the surface of the multi-layered detector structure. Each time the scanner moves from the left to the right side of the detector structure, a stepping motor moves the mirror through a sufficient arc to deflect the beam vertically about the detector structure. This arrangement enables the laser/light source to raster scan the entire surface of the detector.
While this readout means effectively scans the surface of the detector and produces a high resolution image therefrom, there are a number of problems associated with this readout scheme. First, it is difficult to achieve the highly linear and repeatable movement of the mirrors due to the complexity imposed upon the electro-mechanical hardware. Secondly, through the arrangement of mirrors and the nature of the laser, light level stability is a problem which affects the ability to readout and the quality of the final image produced. Thirdly, the alignment of the scanner, with the laser/light source and its associated optics, to the detector is a difficult task. Fourthly, the cost of this type of readout scheme is, on a relative basis, expensive. Both the laser and the electro-mechanical hardware impose a significant cost impact to the overall X-ray readout system. Finally, this arrangement of lasers, mirrors, and electro-mechanical hardware is inherently bulky. The sheer volume of this arrangement inhibits the mobility and portability of this device.
It is an object of the present invention to provide a method and apparatus capable of light emission having a complete raster scan.
It is another object of the present invention to provide a method and apparatus generating a raster scan which is highly linear and easily repeatable.
It is another object of the present invention to provide a method and apparatus that provides a stable light source during the readout of a plate structure.
It is a further object of the present invention to provide a method and apparatus which minimizes the complexity and cost of the scanning hardware.
It is still another object of the present invention to provide a scanning apparatus and method which enhances the portability and minimizes the bulk of the scanning optics.
These and other objects and advantages of the present invention will become apparent from a reading of the attached Specification and appended Claims.